Reviewed by USGSTonga17y ago
M4.3 earthquake 31 km ESE of Hihifo, Tonga
Saturday, December 5, 2009, 07:47:54 UTC · 16.093°S, 173.538°W
A magnitude 4.3 earthquake struck 31 km ESE of Hihifo, Tonga on Saturday, December 5, 2009, 07:47:54 UTC, at a depth of 10.0 km (shallow).
- Magnitude
- 4.3
- Light · mb
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
43 tons of TNT
That is about 1/354 of the Hiroshima bomb. A magnitude 5.0 releases about 11 times more energy.
Tectonic setting
110 km
from the nearest mapped plate boundary, between the Tonga and Niuafo'ou plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
10 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS lists 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.1 on December 12, 2009. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 1,560 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11919 Tonga EarthquakeApril 30, 1919 · 274 km SE of this epicenter
- 8.12009 Samoa EarthquakeSeptember 29, 2009 · 168 km NE of this epicenter
- 8.0The 1917 Samoa-Tonga EarthquakeJune 26, 1917 · 125 km N of this epicenter
- 7.8146 km ESE of Hihifo, TongaDecember 26, 1975 · 116 km E of this epicenter
- 7.7133 km NE of Hihifo, TongaSeptember 1, 1981 · 135 km N of this epicenter
- 7.6199 km ESE of Hihifo, TongaApril 2, 1977 · 168 km SE of this epicenter
- 7.488 km NNE of Hihifo, TongaApril 7, 1995 · 99 km N of this epicenter
- 7.3201 km ENE of Neiafu, TongaOctober 6, 1987 · 248 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 10 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 194 recorded deaths. The most severe:
- 2009M8.1
Samoa Islands
29 Sep 2009 · 168 km away
192 deaths$285 million damagetsunami
- 1917M8.3
Samoa Islands
26 Jun 1917 · 88 km away
2 deathsModerate damage ($1–5M)tsunami
- 1919M8.1
Tonga Islands
30 Apr 1919 · 274 km away
Limited damage (under $1M)tsunami
- 1981M7.7
Apia; American Samoa: Pago Pago
1 Sep 1981 · 135 km away · intensity VI
Limited damage (under $1M)tsunami
- 1977M7.6
Apia
2 Apr 1977 · 168 km away · intensity VI
Limited damage (under $1M)tsunami
- 1975M7.8
Samoa Islands
26 Dec 1975 · 116 km away · intensity V
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.